U.S. patent application number 10/709203 was filed with the patent office on 2005-10-27 for steam turbine rotor temperature control at oil deflector.
This patent application is currently assigned to General Electric Company. Invention is credited to Lavash, John Cleland, Palmer, Gene David, Rivas, Flor Del Carmen.
Application Number | 20050238485 10/709203 |
Document ID | / |
Family ID | 34940816 |
Filed Date | 2005-10-27 |
United States Patent
Application |
20050238485 |
Kind Code |
A1 |
Rivas, Flor Del Carmen ; et
al. |
October 27, 2005 |
STEAM TURBINE ROTOR TEMPERATURE CONTROL AT OIL DEFLECTOR
Abstract
A turbine comprises an oil deflector including at least one set
of seal rings, and a shaft including an annular step. The step
includes a circumferential surface in proximity to the seal rings
of the oil deflector and a side surface extending radially from a
center portion of the shaft and defining a groove positioned
radially underneath the circumferential surface.
Inventors: |
Rivas, Flor Del Carmen;
(Clifton Park, NY) ; Palmer, Gene David; (Clifton
Park, NY) ; Lavash, John Cleland; (Niskayuna,
NY) |
Correspondence
Address: |
NIXON & VANDERHYE P.C.
901 NORTH GLEBE ROAD, 11TH FLOOR
ARLINGTON
VA
22203
US
|
Assignee: |
General Electric Company
1 River Road Building 37, Fifth Floor
Schenectady
NY
|
Family ID: |
34940816 |
Appl. No.: |
10/709203 |
Filed: |
April 21, 2004 |
Current U.S.
Class: |
415/174.5 |
Current CPC
Class: |
F01D 11/003 20130101;
F16J 15/162 20130101; F01D 11/02 20130101; F01D 25/183 20130101;
F01D 5/081 20130101; F16J 15/164 20130101 |
Class at
Publication: |
415/174.5 |
International
Class: |
F03B 011/00 |
Claims
1. A turbine comprising: an oil deflector including at least one
set of seal rings; and a shaft including an annular step, the step
having a circumferential surface in proximity to the seal rings and
a side surface extending radially from a central portion of the
shaft and defining a groove positioned radially underneath the
circumferential surface.
2. A turbine according to claim 1, wherein the step further
includes another side surface extending radially from the central
portion of the shaft, the groove extending axially toward the
another side surface.
3. A turbine according to claim 2, wherein the shaft comprises an
intermediate pressure rotary shaft.
4. A turbine according to claim 1, wherein the shaft further
includes a thrust bearing enclosure which extends radially from the
central portion of the shaft, the step projecting axially away from
the thrust bearing enclosure.
5. A turbine according to claim 4, wherein the shaft comprises a
high pressure rotary shaft.
6. A turbine according to claim 1, wherein the circumferential
surface of the step defines an oil slinger pocket.
7. A rotary shaft of a turbine, the rotary shaft comprising: an
axially extending central portion; and an annular step projecting
radially from the central portion, the step having a
circumferential surface and a radially extending side surface, the
side surface defining a groove positioned radially underneath the
circumferential surface.
8. A rotary shaft according to claim 7, wherein the step further
includes another side surface extending radially from the central
portion of the shaft, the groove extending axially toward the
another side surface.
9. A rotary shaft according to claim 8, wherein the shaft comprises
an intermediate pressure rotary shaft.
10. A rotary shaft according to claim 7, wherein the shaft further
includes a thrust bearing enclosure extending radially from the
central portion of the shaft, the step projecting axially away from
the thrust bearing enclosure.
11. A rotary shaft according to claim 10, wherein the shaft
comprises a high pressure rotary shaft.
12. A rotary shaft according to claim 7, wherein the
circumferential surface of the step defines an oil slinger
pocket.
13. A turbine comprising: a first oil deflector including at least
one set of seal rings; a second oil deflector including at least
one set of seal rings; and a shaft including: a first annular step
having a circumferential surface in proximity to the seal rings of
the first oil deflector; and a second annular step having a
circumferential surface in proximity to the seal rings of the
second oil deflector.
14. A turbine according to claim 13, wherein the first annular step
includes a radially extending side surface which defines a groove
positioned radially underneath the circumferential surface of the
first annular step, and the second annular step includes a radially
extending side surface which defines a groove positioned radially
underneath the circumferential surface of the second annular
step.
15. A turbine according to claim 14, wherein the first annular step
further includes another radially extending side surface, the
groove positioned underneath the circumferential surface of the
first annular step extending axially toward the another side
surface.
16. A turbine according to claim 14, wherein the shaft further
includes a thrust bearing enclosure extending radially from a
central portion of the shaft, the second annular step projecting
axially away from the thrust bearing enclosure.
17. A turbine according to claim 15, wherein the shaft further
includes a thrust bearing enclosure extending radially from a
central portion of the shaft, the second annular step projecting
axially away from the thrust bearing enclosure.
18. A turbine according to claim 13, wherein at least one of the
first and second annular steps includes a radially extending side
surface which defines a groove positioned radially underneath the
circumferential surface of the at least one first and second
annular steps.
Description
BACKGROUND OF INVENTION
[0001] The present invention relates to machines such as turbines,
and more particularly to a turbine having a rotor and an oil
deflector in which the temperature of the rotor near the oil
deflector is reduced.
[0002] FIGS. 1-3 illustrate a section of a known steam turbine. The
steam turbine includes a rotating shaft and an oil deflector.
Bearings of the steam turbine provide lubrication oil. While the
bearing housing confines much of the lubrication oil, some of the
oil leaks and travels axially along the shaft. The oil deflector
confines this oil through a plurality of seal rings or "teeth" to
allow the oil to be drained.
[0003] Due to the relatively high operating temperatures of the
steam turbine, oil in the vicinity of the oil deflector may
carbonize. In particular, oil within the seal rings is prone to
carbonize when subject to high temperatures. The degree of oil
carbonization increases with temperature. The carbonized oil is
often hard enough to damage the rotating shaft. For example, the
carbonized oil is often hard enough to cut grooves in the rotating
shaft. While heat shields and the use of lubrication oil as a
coolant help control temperature to some degree, they have not been
completely successful in preventing oil carbonization at the oil
deflector.
[0004] It would therefore be beneficial to reduce the temperature
of the rotor in the vicinity of the oil deflector to thereby
prevent oil carbonization. Damage to the rotor due to oil
carbonization can therefore be minimized.
SUMMARY OF INVENTION
[0005] A turbine is provided which comprises an oil deflector
including at least one set of seal rings and a shaft including an
annular step. The step has a circumferential surface in proximity
to the seal rings and a side surface extending radially from a
central portion of the shaft and defining a groove positioned
radially underneath the circumferential surface. The step may
further include another side surface extending radially from the
central portion of the shaft, the groove extending axially toward
the another side surface. The shaft may comprise an intermediate
pressure rotor shaft. Alternatively, the shaft may further include
a thrust bearing enclosure which extends radially from the central
portion of the shaft, the step projecting axially away from the
thrust bearing enclosure. The shaft may comprise a high pressure
rotor shaft. The circumferential surface of the step may define an
oil slinger pocket.
[0006] In another exemplary embodiment, a rotary shaft of a turbine
comprises an axially extending central portion and an annular step
projecting radially from the central portion. The step has a
circumferential surface and a radially extending side surface which
defines a groove positioned radially underneath the circumferential
surface. The rotary shaft may be a high pressure rotary shaft or an
intermediate pressure rotary shaft. The step may further include
another side surface extending radially from the central portion of
the shaft, the groove extending axially toward the another side
surface. Alternatively, the shaft may further comprise a thrust
bearing enclosure extending radially from a central portion of the
shaft, the step projecting axially away from the thrust bearing
enclosure. The circumferential surface of the step may define an
oil slinger pocket.
[0007] In another exemplary embodiment, a turbine comprises a first
oil deflector including at least one set of seal rings, a second
oil deflector including at least one set of seal rings, and a shaft
including a first annular step and a second annular step. The first
annular step has a circumferential surface in proximity to the seal
rings of the first oil deflector and the second annular step has a
circumferential surface in proximity to the seal rings of the
second oil deflector. At least one of the annular steps may further
include a radially extending side surface which defines a groove
positioned radially underneath the circumferential surface of that
annular step. For example, the first annular step may include a
radially extending side surface which defines a groove positioned
radially underneath the circumferential surface of the first
annular step and the second annular step may include a radially
extending side surface which defines a groove positioned underneath
the circumferential surface of the second annular step.
BRIEF DESCRIPTION OF DRAWINGS
[0008] FIG. 1 is a cross-sectional view of a known turbine
section;
[0009] FIG. 2 is a detailed cross-sectional view of a part of the
known turbine section illustrated in FIG. 1;
[0010] FIG. 3 is a detailed cross-sectional view of another part of
the known turbine section illustrated in FIG. 1;
[0011] FIG. 4 is a cross-sectional view of a turbine section in
accordance with an exemplary embodiment of the present
invention;
[0012] FIG. 5 is a more detailed view of a part of the turbine
section illustrated in FIG. 4;
[0013] FIG. 6 is a cross-sectional view illustrating, inter alia, a
more detailed view of a part of the turbine section illustrated in
FIG. 4; and
[0014] FIG. 7 is a cross-sectional view illustrating, inter alia, a
more detailed view of another part of the turbine section
illustrated in FIG. 4.
DETAILED DESCRIPTION
[0015] FIGS. 4-7 illustrate a steam turbine in accordance with an
exemplary embodiment. The steam turbine includes, for example,
rotatable shaft 10, oil deflector 30, end packings 40, bearings 42
and oil deflector 60.
[0016] Referring to FIG. 4, shaft 10 includes an intermediate
pressure (IP) rotor shaft portion 20 and a high pressure (HP) rotor
shaft portion 50. IP rotor shaft portion 20 includes stages 27 for
holding buckets (not shown for clarity) upon which intermediate
pressure steam is blown to rotate shaft 10. HP rotor shaft portion
50 includes stages 57 for holding another set of buckets (not shown
for clarity) upon which high pressure steam is blown to rotate
shaft 10. IP rotor shaft portion 20 and HP rotor shaft portion 50
are connected together at joint 43.
[0017] Referring now to FIG. 5, IP rotor shaft portion 20 includes
an annular step 21 which projects radially from center portion 28
of shaft 10. Step 21 includes a circumferential surface 22 which
forms a radially outermost edge portion of step 21. Circumferential
surface 22 defines an oil slinger pocket 26. Oil slinger pocket 26
forms an annular groove which allows oil to be trapped and
collected for drainage. Step 21 also includes two side surfaces 23
and 25 extending in the radial direction away from central portion
28. Surface 23 defines an annular groove 24 which is positioned
radially underneath a portion of circumferential surface 22.
Exemplary (but in no way limiting) dimensions of step 21 are as
follows: w=3.5 inches, h=1.625 inches and g=1.06 inches.
[0018] Referring now to FIG. 6, oil deflector 30 includes heat
shields 33, a set of seal rings 31 and another set of seal rings
32. Heat shields 33 protect seal rings 31 and 32 from radiated heat
transferred from end packings 40. End packings 40 are designed to
prevent steam from leaking toward other turbine components such as
oil deflector 30.
[0019] Seal rings 31 and 32 each encircle a portion of step 21 of
shaft 10. Each of seal rings 31 and 32 has a radially innermost
edge which is in close proximity to circumferential surface 22 of
step 21. A small working clearance is defined between the radially
innermost edge of each of seal rings 31 and 32 and circumferential
surface 22 which forms the radially outermost edge of step 21.
[0020] Seal rings 31 and 32 of oil deflector 30 provide a seal
against oil leakage which travels axially along shaft 10. Oil may
begin leaking, for example, from bearing 42 and travel along shaft
10. An annular chamber 34 is formed between the sets of seal rings
31 and 32 and opposite oil slinger pocket 26 so that the oil can be
collected and drained.
[0021] Step 21 provides a rotor geometry which prevents the
overheating of oil in the area of oil deflector 30. In particular,
annular groove 24 reduces the amount of heat-conductive material
that would otherwise form step 21 and thus diminishes the heat
transferred to the area of rotor 10 near seal rings 31 and 32
through the heat conductive material forming shaft 10. Moreover,
air flowing in groove 24 will cool step 21 and a part of central
portion 28 which is close to groove 24 as shaft 10 rotates at a
high speed. Rotor 10, and hence the oil in the vicinity of rotor 10
and oil deflector 30, will thus not be overheated. In particular,
the temperature of the oil near oil deflector 30 is controlled to
be less than 300.degree. F. Oil carbonization near oil deflector 30
can therefore be prevented, thereby minimizing damage to shaft 10
and oil deflector 30.
[0022] Referring now to FIG. 7, HP rotor shaft portion 50 of shaft
10 includes a thrust bearing enclosure 55 and an annular step 51
which projects axially away from thrust bearing enclosure 55 (step
51 projects in the axial direction opposite of thrust bearing
enclosure 55). Step 51 also extends radially away from central
portion 58 of rotor shaft portion 50.
[0023] Step 51 includes a circumferential surface 52 which forms a
radially outermost edge of step 51. Circumferential surface 52
defines an oil slinger pocket 56. Oil slinger pocket 56 forms an
annular groove 54 which allows oil to be trapped and collected for
drainage. Step 51 also includes a side surface 53 extending in the
radial direction away from central portion 58. Surface 53 defines
an annular groove 54 which is positioned radially underneath a
portion of circumferential surface 52. Exemplary (but in no way
limiting) dimensions of step 51 are as follows: h=2.625 inches and
g=2.4 inches.
[0024] Oil deflector 60 includes heat shields 63, a set of seal
rings 61 and another set of seal rings 62. Heat shields 63 protect
seal rings 61 and 62 and other turbine components from radiated
heat. Seal Rings 61 and 62 each encircle a portion of step 51. Each
of seal rings 61 and 62 has a radially innermost edge which is in
close proximity to circumferential surface 52. A small working
clearance is defined between the radially innermost edge of each of
seal rings 61 and 62 and circumferential surface 52 which forms the
radially outermost edge of step 51. Seal rings 61 and 62 of oil
deflector 60 provide a seal against oil leakage which travels
axially along shaft 10. An annular chamber 64 formed between the
sets of seal rings 61 and 62 and opposite to oil slinger pocket 56
collects oil so that it can be drained.
[0025] Step 51 provides a rotor geometry which prevents the
overheating of oil in the area of rotor 10 near oil deflector 60.
Oil carbonization in the area of oil deflector 60 can thus be
prevented. In particular, annular groove 54 minimizes the amount of
heat conductive material forming step 51 and thus diminishes the
heat transferred to the area near seal rings 61 and 62 through the
heat conductive material forming HP shaft portion 50. Heat
conductive material which is "missing" from step 51 to form annular
groove 54 is thus not available to conduct heat. Moreover, air
flowing in groove 54 will cool step 51 and the part of central
portion 58 which is close to groove 54, particularly as shaft 10
rotates at a high speed. Rotor portion 50, and hence the oil in the
vicinity of oil deflector 60, will thus not be overheated. The
temperature of the oil will remain below 300.degree. F., the
temperature needed for oil to carbonize. Oil carbonization near oil
deflector 60 is thus prevented. Damage to shaft 10 and oil
deflector 60 is therefore minimized.
[0026] While the invention has been described in connection with
what is presently considered to be the most practical and preferred
embodiment, it is to be understood that the invention is not to be
limited to the disclosed embodiment, but on the contrary, is
intended to cover various modifications and equivalent arrangements
included within the spirit and scope of the appended claims. For
example, while shaft 10 includes both steps 21 and 51, shaft 10 may
include only one of steps 21 and 51. That is, shaft 10 may include
an IP rotor shaft portion 20 which includes step 21 and is
connected to a HP rotor shaft portion 50 which does not include
step 51. Alternatively, shaft 10 may comprise HP rotor shaft
portion 50 including step 51 and an IP rotor shaft portion 20 which
does not include step 21.
* * * * *